Welded Diff - Bad idea?

Ron Earp

Ron Earp

Administrator
I've been looking into getting limited slip for the JH I'm building now. However, these things are almost impossible to find, out of production, and were only available in Europe in the 70s I'm told.

What do you think about welding the differential? Have done this on a drag car with good effect, but was wondering how such a thing would treat me on the track? Any comments? Might could also try the Phantom Grip too, but I'm just exploring options at the moment.

Ron

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Ron
http://www.gt40s.com
Lotus Turbo Esprit
BMW E36 M3
RF GT40 Replica
Jensen-Healey: IT prep progressing!
 
I've driven a Welded diff in a FWD car, and I love it. It is very reliable and is responds the same way every time.

The phantom grip is not the hot ticket from what I've read. OPM or housman motorsports might be able to make a diff for you.

Alan
 
Ron, if you can't find a lsd for your car, then you really don't have any other option than a welded diff. They work fine for road racing, although having a lsd is better. The biggest problem with the welded diff is that it's hard to push around the shop/paddock, and there is a bit more wear and tear on axles and such.
With a rear drive car, you won't have to change driving styles all that much with a locked rear end. Wet weather driving will be a bit more twitchy, but again nothing that can't be overcome. I would stay away from phantom grip. I have not heard much positive about them, especially in race cars.

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Tristan Smith
Buffalo's Southwest Cafe
ITA Nissan 240sx #56
 
I'm going to keep trying to get the LSD but if I cannot then we'll weld it. A couple of guys on my forum for GT40s have tried the Phantom Grip and it didn't work. But, it was also behind a 525 hp SB Ford too, so the out come was sort of indeterminiable.

Prepping an older car has some advantages, i.e. simplicity, but any Brit car isn't the easiest thing in the world to get a good selection of parts for.

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Ron
http://www.gt40s.com
Lotus Turbo Esprit
BMW E36 M3
RF GT40 Replica
Jensen-Healey: IT prep progressing!
 
On a short, twisty track like Blackhawk Farms, a welded diff in a front drive car is a blast. You can really flaten out the turns by launching the inside tires, and the outside run an arc that just hits the curb.
 
Be sure that if you weld the differential that you weld both the spiders...and between each of the gear teeth. Just realized that this is what was causing us to scatter welded rear ends. They work fine for orad racing...

Ed
 
Guys, get this, the LSD for the Jensen-Healey was only offered on something called a "Vauxhall Dropsnoot Firenza." Too much.

Ron, I'm back from CMP. Lots of stories, one of which is I met a guy who has a shop in Charleston, SC who specializes in J-Hs. He has a limited slip. I'll talk to you tonight.

Wonder of wonders.

Jeff
 
Ron, I've been running a welded diff on my VW's for about 10 years. Like stated above, it's just a little bit more bother makine 90 degree turns in the paddock, but once you get over that, it's a blast to drive.

No, there is NOT more wear and tear on the CV's and hubs. As part or normal maintenance, you should change out your CV's and hubs every year anyway. I've only lost 1 CV joint while on track the last 10 years.

I broke more front end stuff with an open front diff while auto-crossing thatn I have done road racing.



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Tim Linerud
San Francisco Region SCCA
#95 GP Wabbit
http://linerud.myvnc.com/racing/index.html
 
You might not be asking the right question in your parts search. I would not be at all surprised if the diff weren't some third-party assembly, given the relatively low production numbers involved.

The Vauxhall Firenza "Droopsnoot" was part of a family of cars that were all essentially the same critter under the bodywork. There were several high-performance variants of the Cavalier (a little bigger) and Chevette (a little smaller) offered in Great Britain.

You might try the vintage rally people in England or Europe, or even the lunatic fringe of the rallyist fraternity here in the states. The Chevette (RS?) and the Opel Kadett (they were all GM Europe brands) were very popular club rallying platforms and the guts of the third members MIGHT be the same.

K
 
I ran a welded diff on my ITS 240Z for several years. Obviously not as good as a well set up LSD but waaaaaaaaaaaaaaaay more affordable. Absolutely zero failures but then again I took it to a guy who knew how to properly weld it up. I kept an open rear to swap out on really wet tracks and did just fine.

Before I welded it up I used an open rear...the welded set up got me around 2-4 second decrease on lap times depending on the track.

Note that you will end up with a noticeable push and have to adjust your sway bar settings to compensate.

Overall the best performance mod I ever made given my limited budget.
 
<font face=\"Verdana, Arial\" size=\"2\">Another person to talk to is Tom Fowler at OPM. www.opmautosports.com. He has a NC contact who can build a LSD for almost anything. And a damn good one too.</font>
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I have an OPM unit in my Suzuki Swift. After hard testing at both tracks and hillclimbs, I can honestly say that it is absolutely worthless except for wet situations...
 
Roy,

Did you ever discuss this with Tom at OPM? Yours is the first complaint about a diff I've heard of since I've known Tom (about 4 years). I know of several ARRC winners using an OPM diff.

Tom
 
The OPM and the Phantom Grip both are torque sensing units. The more torque they are handling, the more they hold. They won't work on the Suzuki Swift because it lifts a front wheel in the corners. It can't apply torque to a wheel in midair, so the limited slip doesn't hold. Welding is the best solution for the Swift, but the OPM or Phantom Grip work fine in most all front drivers.
 
Joeg- Yes we run the Phantom Grip in all our Hondas, and have been for 5 years. Fifty races on one before the car was totaled at VIR. Pulled it out, inspected it and put it back in the replacement car. Two ARRC wins, SARRC Champions, etc. Bring an ITC to Atlanta Motor Speedway this weekend and you are likely to finish no better than third behind our cars with the Phantom Grips. (g)
 
I run a Phantom grip in my Honda ITC car also. I noticed a HUGE difference in comparison to an open diff. It's only been in since the begining of this year, so I don't have any reliability advice for you.

wbp, could you hit me up via email sometime? I have a couple questions about my Honda if you have a few minutes and are willing.

Thanks
 
Ok, so this thread is a bit old, but the discussion about the Phantom Grip got my attention. For those of us who will be running on a limited budget, it seems pretty attractive. Would those of you who have experience with it say its better than a welded diff? Ive also heard about the reliablitiy factor, but does that come into play with a car that has HP figures that are less than 160 (i.e. ITA and ITB cars)?
 
It works fine, but is tough on the components and a real Bi*ch to move around the paddock. I also managed to brake a high quality axle this way (11 other years with LSD never broke one)

Originally posted by rlearp:
I've been looking into getting limited slip for the JH I'm building now. However, these things are almost impossible to find, out of production, and were only available in Europe in the 70s I'm told.

What do you think about welding the differential? Have done this on a drag car with good effect, but was wondering how such a thing would treat me on the track? Any comments? Might could also try the Phantom Grip too, but I'm just exploring options at the moment.

Ron
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